Influence of irradiation-induced defects on fracture behavior in highly pure SiC

Charged-particle irradiation to highly pure SiC was performed to investigate the influence of irradiation-induced defects on its fracture behavior. To investigate the fracture behavior of SiC, the microstructural analysis was carried out by observing cross-sections of a residual indentation impression. An apparent increase of indentation fracture toughness was shown in the highly pure SiC upon ion irradiation. In the case of ion-irradiated SiC, a number of micro-cracks were created around the indentation-induced deformation region. Indentation-induced slip bands on the (1 1 1) crystallographic plane were observed in both the virgin and the ion-irradiated SiC. The indentation-induced slip bands and the pre-existing defects provided one of the sites for micro-crack creation for the ion-irradiated SiC. The formation of the micro-cracks may dissipate the fracture energy for brittle fracture, which seems to be one of the mechanisms for the toughening behaviors of SiC by an energetic particle irradiation.